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Why are rapidly rotating M dwarfs in the Pleiades so (infra)red? New period measurements confirm rotation-dependent color offsets from the cluster sequence

Covey, Kevin R. and Agüeros, Marcel A. and Law, Nicholas M. and Liu, Jiyu and Ahmadi, Aida and Laher, Russ and Levitan, David and Sesar, Branimir and Surace, Jason (2016) Why are rapidly rotating M dwarfs in the Pleiades so (infra)red? New period measurements confirm rotation-dependent color offsets from the cluster sequence. Astrophysical Journal, 822 (2). Art. No. 81. ISSN 0004-637X.

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Stellar rotation periods (P_(rot)) measured in open clusters have proved to be extremely useful for studying stars' angular momentum content and rotationally driven magnetic activity, which are both age- and mass-dependent processes. While P rot measurements have been obtained for hundreds of solar-mass members of the Pleiades, measurements exist for only a few low-mass (<0.5 M_⊙) members of this key laboratory for stellar evolution theory. To fill this gap, we report P_(rot) for 132 low-mass Pleiades members (including nearly 100 with M ≤ 0.45 M_⊙), measured from photometric monitoring of the cluster conducted by the Palomar Transient Factory in late 2011 and early 2012. These periods extend the portrait of stellar rotation at 125 Myr to the lowest-mass stars and re-establish the Pleiades as a key benchmark for models of the transport and evolution of stellar angular momentum. Combining our new P_(rot) with precise BVIJHK photometry reported by Stauffer et al. and Kamai et al., we investigate known anomalies in the photometric properties of K and M Pleiades members. We confirm the correlation detected by Kamai et al. between a star's P_(rot) and position relative to the main sequence in the cluster's color–magnitude diagram. We find that rapid rotators have redder (V − K) colors than slower rotators at the same V, indicating that rapid and slow rotators have different binary frequencies and/or photospheric properties. We find no difference in the photometric amplitudes of rapid and slow rotators, indicating that asymmetries in the longitudinal distribution of starspots do not scale grossly with rotation rate.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Covey, Kevin R.0000-0001-6914-7797
Agüeros, Marcel A.0000-0001-7077-3664
Law, Nicholas M.0000-0001-9380-6457
Laher, Russ0000-0003-2451-5482
Sesar, Branimir0000-0002-0834-3978
Surace, Jason0000-0001-7291-0087
Additional Information:© 2016 The American Astronomical Society. Received 2015 September 16; accepted 2016 January 12; published 2016 May 10. We are grateful to Eran Ofek for his help scheduling and carrying out the PTF observations, to Adrian Price-Whelan for his help extracting light curves from the PTF database, and to Aaron Dotter for providing a 125 Myr isochrone with colors computed in the specific filters used during the course of this analysis. We also thank John Stauffer, Luisa Rebull, Kristen Larson, and the anonymous referee for comments that improved our analysis and presentation of our results. K.R.C. thanks Hilary Schwandt and the WWU Faculty Research Writing Seminar for sage advice that accelerated the completion of this manuscript, and acknowledges support provided by the NSF through grant AST-1449476. M.A.A. acknowledges support provided by the NSF through grant AST-1255419. Observations were obtained with the Samuel Oschin Telescope as part of the Palomar Transient Factory project, a scientific collaboration between the California Institute of Technology, Columbia University, Las Cumbres Observatory, the Lawrence Berkeley National Laboratory, the National Energy Research Scientific Computing Center, the University of Oxford, and the Weizmann Institute of Science. The Two Micron All-Sky Survey was a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center (California Institute of Technology). The University of Massachusetts was responsible for the overall management of the project, the observing facilities and the data acquisition. The Infrared Processing and Analysis Center was responsible for data processing, data distribution and data archiving. This research has made use of NASAʼs Astrophysics Data System Bibliographic Services, the SIMBAD database, operated at CDS, Strasbourg, France, and the VizieR catalog access tool, CDS, Strasbourg, France (Ochsenbein et al. 2000). This research was made possible through the use of the AAVSO Photometric All-Sky Survey (APASS), funded by the Robert Martin Ayers Sciences Fund.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Robert Martin Ayers Sciences FundUNSPECIFIED
Subject Keywords:open clusters and associations: individual (M44, Pleiades) ; stars: late-type; stars: low-mass; stars: rotation; starspots
Issue or Number:2
Record Number:CaltechAUTHORS:20160701-065540168
Persistent URL:
Official Citation:Kevin R. Covey et al 2016 ApJ 822 81
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:68796
Deposited By: Ruth Sustaita
Deposited On:01 Jul 2016 14:55
Last Modified:02 Nov 2019 03:00

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